According to a note posted on the singer's Web site and Facebook page on Monday morning (April 26), the 47-year-old rocker "remains in ICU under 24-hour surveillance. Further testing this week will help locate the source of the bleeding."

The singer is reportedly suffering from slurred speech, blurred vision and dizziness as a result of the hemorrhage.

Michaels was rushed to the hospital late Thursday evening, where doctors discovered he had suffered a subarachnoid hemorrhage, or bleeding at the base of his brain stem, a rep for the singer confirmed to MTV News.

"After several CAT scans, MRIs and an angiogram, [doctors] decided to keep Michaels in the ICU and are running several tests to determine the cause [of the hemorrhage]," a source told People magazine, in a report that Michaels' rep said was accurate. "[It] will be touch and go for the next few days while he is under intense observation."

Michaels, who was diagnosed with diabetes as a child, had an emergency appendectomy earlier this month, an event he called a "wake-up call to be a little bit more diligent on keeping control of my health" in a blog post. The reality-TV star is currently featured on "The Celebrity Apprentice," and the show — filmed several months ago — made a brief reference to his illness on Sunday night's episode. A post-script found Michaels walking in slow motion across an airport tarmac with a voiceover intoning, "Everyone here at NBC wishes Bret Michaels a speedy recovery."

While recovering at his Texas home from the emergency appendectomy, Michaels was struck on Thursday by a blinding headache that prompted a 911 call. People magazine reported that an unnamed source said Michaels was suffering from excruciating pain from the headache just moments before he was rushed to the emergency room. The source said Michaels described headache as feeling like "[getting] hit in the head with a baseball bat over and over again."

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